The elevator installation is installed in a shaft. It substantially consists of a car connected with a drive by way of support means. The car is moved along a car travel path by means of the drive. The support means are connected with the car by way of deflecting rollers with a multiple slinging. The load-bearing force acting in the support means is reduced by the multiple slinging in correspondence with a slinging factor. The car is designed to transport a useful load which can vary according to the respective need between empty (0%) and full (100%).
An elevator suspension of that kind with a car and a deflecting roller arrangement, which is mounted at the car frame, is known from German patent DE 20 221 212, wherein the deflecting roller arrangement comprises at least two deflecting rollers which are rotatable about a common axle.
A further elevator installation of that kind with two deflecting rollers arranged in parallel is known from European patent EP 1 446 348, wherein the deflecting rollers are arranged symmetrically with respect to a car guide.
Elevator installations of that kind usually include a load measuring system which, for example, is to detect an overload in the car or which measures an effective useful load so as thus to be able to preset a required drive torque for the drive. An overload exists when the useful load is more than 100% of the useful load or which the car is designed. In many cases load measuring systems of that kind are arranged in a car floor, in that, for example, deformations or spring deflections of the car floor are measured, or stress measuring elements are mounted at load-bearing structures of the car.
Proceeding from the known state of the art the object now arises of demonstrating a load measuring system for an elevator installation with deflecting rollers arranged in parallel, the system being able to be integrated simply and favorably in cost in an elevator installation and being capable of measuring the useful load of the car with sufficient accuracy. Moreover, use shall advantageously be able to be made of economic measuring elements.